In many cases, desirable properties can be imparted to polycarbonates and other polymers by reacting together one or more aromatic dihydroxy monomers via melt or interfacial polymerization process to form polycarbonate homopolymers and copolymers. In such cases, it is often desirable to obtain random incorporation of the monomers along the polymeric backbone to achieve desirable physical properties. This can be difficult to achieve by melt or interfacial polymerization essentially due to the inherent difference in reactivity of the monomers. It becomes even more challenging when aromatic dihydroxy compounds are copolymerized with aliphatic diols which present, for example, secondary alcohols, such as for example cyclobutane diols, for which the pKa is greater than commonly used bisphenols. The efficient polymerization of such compounds involves a significant number of trade-offs. For example, one can compensate for low reactivity by altering the amount of catalyst introduced into the system, but the temperature and reaction time would lead inherently to lower optical properties of the final polymeric material (e.g. yellowness and transparency).
It is known to prepare polymers from certain cyclobutanediols such as from tetramethylcyclobutanediol (TMCBD) and aromatic dihydroxy compounds such as bisphenol A (BPA). However, preparation of the polymers employs solvents and high temperatures. U.S. Pat. Nos. 3,326,855, 3,313,777, 3,546,331, 3,546,332, 3,541,200, 3,375,210, and 3,674,623 disclose such polymers prepared from TMCBD. U.S. Pat. No. 5,965,688 discloses a method for making tetramethylcyclobutanediol-containing polycarbonates via interfacial polymerization involving aliphatic haloformates, prepared prior to the reaction, with aryl dihydroxy compounds.
The reaction of this invention relates to the polymerization of a bisphenol of TMCBD that permits copolymerization with other dihydroxy compounds.